Stations along the Vistula River transect have been sampled and two sequential incubations have been performed to measure denitrification and DNRA (Dissimilatory Nitrate Reduction to Ammonium) rates. Laboratory activities were carried out together with dr hab. Urszula Janas prof. UG, dr Halina Kendzierska, MSc Radosław Brzana, MSc Natalia Miernik and students from the Institute of Oceanography: Kamila Stycz-Olesiak and Zuzanna Czenczek, in collaboration with Monia Magri from the University of Parma (Italy).